Bioindicator species are increasingly being used for environmental monitoring and impact assessment, so the more diverse the ecological options in terms of ecological niches are the test organisms, the greater are the environmental protection and the ability to mitigate damage. The amphipods consist in a group of important organisms in the trophic web and, therefore, are considered good indicators. The species Parhyale hawaiensis has a promising future as a test organism by already meeting the requirements, which are ease of cultivation in the laboratory, generation period relatively short, relative sensitivity to toxic compounds, reproduction throughout the year and be susceptible to experimental manipulations. Although, they already have a number of advantages to be used as test organisms, these amphipods still lack basic studies, such as the description of their hemolymph cells and their basic histology. Hemocytes can be used for cytogenotoxic analyzes, such as the comet assay and nuclear abnormality assay, which could be performed to assess the damage of the genetic material that the contaminants could cause. Histopathological changes generated by pollutants could also be evaluated with a better knowledge of the basic histology of the species. Therefore, this work intends to carry out studies on the basic biology of P. hawaiensis to develop protocols for cytogenotoxic analysis and histopathological changes to evaluate the effect of contaminants in this species. In order to test these protocols developed, the amphipods will be exposed via feeding to silver nanoparticles. Nanoparticles are defined by their size between 1 and 100nm and are being increasingly used in industry, but their behavior in different ecosystems and the damage they cause in organisms are not yet fully known. Silver nanoparticles are widely used as a bactericide in a number of products, such as cosmetics, clothing and detergent, having the highest commercialization rates among metal nanoparticles, increasing the risk of being discarded in larger quantities in the environment. In addition, there is still a possibility of using silver nanoparticles as an antifouling agent in the marine environment, which would increase its concentration even further. The most accepted mechanism of action of these nanoparticles is through the generation of reactive oxygen species, known to be highly reactive and cause various damages, such as oxidation of lipid membranes, proteins and alteration in nucleic acids of cells. Therefore, it would be important to evaluate the effect that the nanoparticles could have on the genetic material and also on the organs of the amphipods P. hawaiensis.
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